Liquid composition



Patented June 4, 1935 UNITED STATES PATENT OFFICE LIQUID COMPOSITION Henry L. Cox,.South Charleston, W. Va., assignor to Carbide and Carbon Chemicals corporation, a corporation of New York 1 I No Drawing. Application October 17, 1931, Serial No. 569,541

5 Claims.- (01. 252-5) This invention relates to fluid mixtures which ethylene glycol and dipropyleneglycol, or trifreeze only at very low temperatures and which ethylene glycol and glycerol have boiling points are useful as heat and pressure transferring less than 20 C. apart, change in composition media and the like. 7 only slowly an evaporation, boil considerably 5 Fluids used for heat transfer, for example in above the boiling point of water, and have very 5 the cooling systems of internal combustion enlow freezing points. Mixtures composed of S es, are frequently called upon to operate over roughly equal volumes of each component will a wide temperature range, and it is desirable that not solidify at temperatures as high as --50 0., they do not vaporize rapidly or change in comand do not tend to change rapidly in composition 10 position at the higher nor solidify at the lower upon evaporation, as shown by the fact that the 10 temperatures of the operating range. In the components cannot be readily separated by ordicooling systems of aircraft engines the conditions nary fractional distillation. are particularly severe, inasmuch as fuel efliciency The flash points of all of these polyhydric aland heat transfer efliciency are improved when cohol mixtures are high, which is of great adthe temperature of the engine and cooling fluid vantage when the fluid is to be used as a coolant 15 are raised; the cooling fluid must withstand high for aircraft engines. The following table shows temperatures and yet not solidify at temperatures the points and flash points of the comwhich are well below the freezing point of water. ponents of several typical mixtures, and also the Low-freezing fluids are desirable also as prcsflash points of the mixtures when composed ofsurctransierring media,usedforexampleinshock about equal portions of each constituent. The 20 absorbers, fluid-pressure lifts, gun-recoil mechaboiling point of each mixture is intermediate benisms and the like. tween the boiling points of the constituents For these purposes it has been customary to use that mixture. mixtures of water with monohydroxy and polyhy- I droxy alcohols such as methanol, ethanol, the Benin int Flash point glycols and glycerol, or a single substantially Mmm of 5 2 mingle fimt anhydrous high-boiling alcohol such as ethylene glycol or diethylene glycol. The aqueous mixtures, while they freeze only at temperatures below the Ethylene glycol 195: 0. 116: 0. s Q freezing point of water, suffer from a number of Pmpylem 187 I 30 disadvantageous characteristics which make them Diethylene glycol 245: o. 141: 0. Q unsuitable for use above moderate temperatures: Dipmpylm" glywh" 117 they are characterized by a low flash point, high Triethylenc glycoln 290: 0. 166: 0. Q vapor pressure, and a tendency for unequal rates 61mm 2 174 of evapora on of the components which results 35 in a progre ive. change in composition, and this It will be obvious t t th i ture of any change in results in thel'aising of the two or more polyhydroxy alcohols may be used for ne nt of t mixturee ly s, used sin y certain purposes. Such mixtures will possess are not as objectionable in these respects, but are low freemng points and high boiling points equal 40 characterized by a freezing-temperature which is to or higher than the boiling point of the lowest 40 Inna! from that of Waten boiling component. Where the vaporizing char- It is the Principal Object O my invention to acteristics of the mixture are not of great imvide a numbe o fl d mixtures which P085885 the portance, as for example in shock absorbers and valuable characteristics that they solidify only at the 111m, any, of t anhydrous mixtures of the extremely low temperatures, below '50 0., have polyhydroxy .a1ooh01s are useful, It is evident 45 low vapor Pressures relative to and markedly therefore that I should not be limited by or to hi her fl s points t an water and wh Y the specific examples used herein, but should be ized change very slowly in composition. limited only to the principle of my invention as I have discovered that the objects of my indis m ed in this specification and defined in the vention may be secured. by the use of substanappended claims, I

tially anhydrous mixtures of p yhydric al- I i I 0 11 preferably having boilin p in s mi 1. Medium for transferring heat or pressure rated by less than about 20 C. For example, consisting of a substantially anhydrous mix? substantially anhydrous 1 mixtures comprising ture of t; least'two polyhydric, alcohols which ethylene glycol and pr pylene gly or difreezes at a temperature below about -5 0' (3., 55

the boiling points of the individual alcohols being separated by less than about 20 C;

2. Liquid composition for transferring heat or pressure consisting of a substantially anhydrous mixture of at least two polyhydric alcohols which freezes at a, temperature below about -50 C. and boils above about 180 C., the boiling points of the individual alcohols being separated by less than about 20 C.

3. Heat transfer medium which consists of a substantially anhydrous mixture in approximate- 1y equal proportions of ethylene glycol and propylene glycol. 4. Heat transfer medium which consists of a substantially anhydrous mixture in approximately equal proportions of diethylene glycol and dipropylene glycol.

5. Heat transfer medium which consists of a substantially anhydrous mixture in approxlmate- 

